revsetbenchmark: add entry for ::rev:: Revsets of the form ::rev:: were identified as the source behind the regressions in issue 4201. Ensure we have explicit coverage of that revset.

all()
draft()
::tip
draft() and ::tip
0::tip
roots(0::tip)
author(lmoscovicz)
author(mpm)
author(lmoscovicz) or author(mpm)
tip:0
max(tip:0)
min(0:tip)
0::
min(0::)
::p1(p1(tip))::